What is oral gavage?
Oral gavage is a procedure used commonly in animal research to deliver a substance directly into an animal’s stomach. It involves restraining a conscious animal and repeatedly forcing a tube or rigid needle down its throat
Why is oral gavage used?
Gavage allows researchers to control exactly how much of a substance an
animal receives, unlike consumption through food or drinking water. This makes it particularly common in studies investigating the effects of oral exposure to a substance, where a precise dose is desired.
Common applications include:
- Toxicology – assessing the potential harmful effects of chemicals or other substances
- Drug development – administering candidate drugs during preclinical research
- Pharmacokinetics – investigating how a substance is absorbed, distributed, metabolised and eliminated
- Chemical safety testing – assessing substances as part of regulatory safety studies
- Disease research – testing compounds that may have potential as treatments
What’s wrong with oral gavage?
Injury and death:
It may sound relatively simple. But in practice, oral gavage involves restraining a conscious animal and repeatedly forcing a tube down its throat. The procedure is violent, invasive and carries a risk of serious injury and death. For example, incorrect positioning can cause the tube or needle to enter the respiratory tract, or perforate the oesophagus, trachea or stomach.
A 2025 study examining 300 repeated-dose toxicity studies involving rats found that 21% reported at least one death or clinical sign attributed to gavage. 14% of the studies reported at least one death attributed to the procedure. Across the 20,180 animals included in the studies, 78 deaths were attributed to gavage — equivalent to a reported risk of approximately one death for every 250 animals. These findings suggest that the harms associated with oral gavage are not simply rare accidents, but a recurring consequence of a procedure that remains routine in animal experimentation.
The study also highlights a potentially important problem with how these harms are recognised. Some clinical signs consistent with gavage-related injury were reported but not attributed to the procedure itself, meaning the true extent of gavage-associated harm may be underestimated. Gavage-related reflux is one example; it occurs when the administered substance moves back towards the nasal cavity and is inhaled into the lungs. Animals may develop breathing difficulties, excessive salivation, nasal discharge, and in some cases this can be fatal.
Relevance to humans:
In many of its applications, the aim is to understand what a substance might do in humans. Yet the method used to administer it can itself affect the animal’s physiology; gavage has been associated with changes in blood pressure, heart rate, body temperature and stress hormones. Repeated gavage has also been linked to reduced weight gain and weight loss, as well as lesions affecting the oral cavity, trachea and lungs.
This creates an important scientific consideration: if the procedure itself causes physiological changes, how confidently can researchers distinguish those effects from the effects of the substance being tested?
A better way exists
There are already approaches that can reduce the need for forced gavage. Voluntary oral dosing, for example, allows animals to consume substances themselves, rather than having them forcibly delivered into the stomach. Researchers have also investigated ways to reduce the harms of oral gavage, such as equipment modification and anaesthesia.
But reducing the harm is only the first part of change. The more important question to ask is whether we need to use animals for these experiments in the first place, when there are already safer, more effective and more ethical options that are animal-free. Among these methods are human intestinal organoids, organ-on-chip systems, in vitro digestion models and computational approaches — all offering ways to investigate drug absorption, toxicity and other biological effects—without subjecting animals to gavage.
Human intestinal organoids:
Human intestinal organoids are three-dimensional models grown from human cells that can reproduce important features of the human gastrointestinal tract. They can be used to investigate processes such as intestinal toxicity, drug absorption and interactions between substances and intestinal cells. They offer significant potential for animal-free drug development and safety testing, and their results are already human-specific.
Organ-on-a-chip:
More sophisticated organ-on-chip and microphysiological systems can recreate aspects of human organ function under controlled laboratory conditions. Gut-on-chip systems, for example, can incorporate human intestinal cells within a dynamic environment designed to reproduce aspects of the gastrointestinal tract. Microphysiological systems are increasingly being developed for investigating drug absorption, metabolism and toxicity and are an important component of the emerging NAMs landscape.
In vitro digestion and human cell models:
In vitro digestion systems can simulate exposure to conditions in the mouth, stomach and intestine. The resulting material can then be investigated using human intestinal models, cell cultures and other human-relevant systems.
Computational modelling:
Computer-based approaches can complement other NAMs by predicting absorption, distribution, metabolism, toxicity and other biological effects. They then connect data from human-relevant in vitro systems with expected exposure and effects in people.
Increasingly, the most powerful approach is not a single “replacement” for an animal experiment, but a combination of human-relevant methods that address different parts of the scientific question.
Key take-aways
The findings from Taylor, Rego Alvarez and Grange should prompt researchers and regulators to reconsider the routine use of oral gavage. While voluntary dosing and equipment modification can reduce the suffering associated with forced gavage, the goal should be to replace it entirely with modern, more ethical alternatives. Because science should not be limited by the assumption that a rat must be force-fed a substance in order to predict what it might do to a person!
The future of science should be human-relevant, scientifically robust — and animal-free.